test(cold-paths): cover 3 lines in mama/rsi/sine_wave (#58)

* test(cold-paths): cover phase fallback in mama/sine_wave and rsi naive helper saturation

* fix(rsi): drop redundant closure in test helper

crates/wickra-core/src/indicators/mama.rs

@@ -369,13 +369,13 @@ mod tests {
 
     #[test]
     fn flat_input_uses_phase_fallback() {
-        // A perfectly constant series leaves every smooth/detrender slot at
-        // the same value, so `i1` collapses to zero and the phase calc takes
-        // the `self.prev_phase` fallback rather than `atan(q1/i1)`. Stretch
-        // the run long enough to clear the 50-bar warmup with comfortable
-        // margin and confirm the indicator still emits.
+        // Zero inputs make every smooth/detrender term arithmetically exact
+        // zero, so `i1 == 0.0` and the phase calculation takes the
+        // `self.prev_phase` fallback rather than `atan(q1/i1)`. A non-zero
+        // constant like `50.0` leaves a sub-EPSILON cancellation residue
+        // that flips the branch back to the `atan` path on real hardware.
         let mut mama = Mama::classic();
-        let out = mama.batch(&[50.0_f64; 200]);
+        let out = mama.batch(&[0.0_f64; 200]);
         assert!(out.iter().flatten().count() > 100);
     }
 }

crates/wickra-core/src/indicators/rsi.rs

@@ -230,6 +230,20 @@ mod tests {
         }
     }
 
+    /// Cover the `100.0` branch (line 169) of the test-helper `rsi_naive`:
+    /// strictly increasing prices give `avg_loss == 0` while `avg_gain > 0`,
+    /// the textbook overbought saturation case. Random proptest inputs
+    /// virtually never satisfy `al == 0 && ag != 0`, so this needs an
+    /// explicit monotone series.
+    #[test]
+    fn naive_helper_monotone_up_yields_100() {
+        let prices: Vec<f64> = (1..=20).map(f64::from).collect();
+        let ks = rsi_naive(&prices, 5);
+        for r in ks.into_iter().skip(5) {
+            assert_eq!(r.expect("ready after period+1 inputs"), 100.0);
+        }
+    }
+
     #[test]
     fn warmup_period_is_period_plus_one() {
         let rsi = Rsi::new(14).unwrap();

crates/wickra-core/src/indicators/sine_wave.rs

@@ -218,11 +218,13 @@ mod tests {
 
     #[test]
     fn flat_input_uses_phase_fallback() {
-        // A constant series leaves the detrender chain at zero, so the `i1`
-        // arm is `i1.abs() <= EPSILON` for every bar and the phase calculation
-        // takes the `self.last_phase` fallback rather than `atan(q1/i1)`.
+        // Zero inputs make every smooth/detrender term arithmetically exact
+        // zero (no IEEE-754 cancellation residue), so `i1 == 0.0` and the
+        // phase calculation deterministically takes the `self.last_phase`
+        // fallback rather than `atan(q1/i1)`. A non-zero constant like
+        // `100.0` leaves a sub-EPSILON residue that flips the branch back.
         let mut sw = SineWave::new();
-        let _ = sw.batch(&[100.0_f64; 120]);
+        let _ = sw.batch(&[0.0_f64; 120]);
         assert!(sw.value().is_some());
     }
 }